package com.study.service.impl;

import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.study.config.RedissinConfig;
import com.study.dto.Result;
import com.study.entity.SeckillVoucher;
import com.study.entity.VoucherOrder;
import com.study.mapper.VoucherOrderMapper;
import com.study.service.ISeckillVoucherService;
import com.study.service.IVoucherOrderService;
import com.study.utils.RedisIdWorker;
import com.study.utils.SimpleRedisLock;
import com.study.utils.UserHolder;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import java.time.LocalDateTime;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Autowired
    private ISeckillVoucherService iSeckillVoucherService;

    @Autowired
    private RedisIdWorker redisIdWorker;

    @Autowired
    private StringRedisTemplate redisTemplate;

    @Autowired
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> REDISSCRIPT;

    private IVoucherOrderService o;

    static {
        REDISSCRIPT = new DefaultRedisScript<>();
        REDISSCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        REDISSCRIPT.setResultType(Long.class);
    }

    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }


    /*@Override
    public Result seckillVoucher(Long voucherId) {

        SeckillVoucher voucher = iSeckillVoucherService.getById(voucherId);
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            return Result.fail("秒杀还没开始！");
        }
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            return Result.fail("秒杀已经结束！");
        }
        if (voucher.getStock() < 1) {
            return Result.fail("优惠券库存不足！");
        }
        Long userId = UserHolder.getUser().getId();
        *//*SimpleRedisLock simpleRedisLock = new SimpleRedisLock("order:" + userId, redisTemplate);*//*
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        boolean tryLock = lock.tryLock();
        if(!tryLock){
            return Result.fail("用户已购买过");
        }
        try {
            VoucherOrderServiceImpl o = (VoucherOrderServiceImpl) AopContext.currentProxy();
            return o.createOrder(voucherId);
        }catch (Exception e){
            throw new RuntimeException();
        }finally {
            lock.unlock();
        }
    }*/

    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);

    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    // 1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {

        RLock lock = redissonClient.getLock("lock:order:" + voucherOrder.getUserId());
        boolean tryLock = lock.tryLock();
        if (!tryLock) {
            log.error("不允许重复下单");
            return;
        }
        try {

            o.createVoucherOrder(voucherOrder);
        } catch (Exception e) {
            throw new RuntimeException();
        } finally {
            lock.unlock();
        }

    }

    public void createVoucherOrder(VoucherOrder voucherOrder) {
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();

        // 5.1.查询订单
        int count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        // 5.2.判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            log.error("不允许重复下单！");
            return;
        }

        // 6.扣减库存
        boolean success = iSeckillVoucherService.update()
                .setSql("stock = stock - 1") // set stock = stock - 1
                .eq("voucher_id", voucherId).gt("stock", 0) // where id = ? and stock > 0
                .update();
        if (!success) {
            // 扣减失败
            log.error("库存不足！");
            return;
        }

        // 7.创建订单
        save(voucherOrder);

    }

    @Override
    public Result seckillVoucher(Long voucherId) {
        Long userId = UserHolder.getUser().getId();
        // 1.执行lua脚本
        Long result = redisTemplate.execute(
                REDISSCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString()
        );
        int r = result.intValue();
        // 2.判断结果是否为0
        if (r != 0) {
            // 2.1.不为0 ，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 2.2.为0 ，有购买资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        // 2.3.订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 2.4.用户id
        voucherOrder.setUserId(userId);
        // 2.5.代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6.放入阻塞队列
        orderTasks.add(voucherOrder);

        //获取代理对象
        o = (IVoucherOrderService) AopContext.currentProxy();
        // 3.返回订单id
        return Result.ok(orderId);
    }
}
